Cerebral Events are not Predicted by Near-Infrared Spectroscopy during Anesthesia for Aortic Arch Surgery with Bilateral Antegrade Selective Cerebral Perfusion and Hypothermic Circulatory Arrest

Background: Near-infrared spectroscopy (NIRS) for brain monitoring has an uncertain value. We prospectively assessed the association of decreased NIRS tissue oxygenation index (TOI) with cerebral events in adults undergoing aortic arch repair with hypothermic circulatory arrest and bilateral antegrade selective cerebral perfusion. Methods: 76 consecutive patients (mostly aortic arch dissections/aneurysms) were studied. Desaturation was defined as unilateral or bilateral TOI decrease to <50% or to <80% of the individual patients’ baseline. No intervention was based on TOI data and the end-point was postoperative cerebral events shown by imaging. Results: Baseline TOI on left/right foreheads averaged 70.4% ± 10.8 (SD) and 67.9% ± 9.1, and did not change significantly thereafter. Twentysix of 76 patients (34%) showed a TOI decrease to <50% and 55 (72%) a decrease to <80% from baseline. Cerebral complications occurred in 26/76 patients (34%), i.e., regional brain infarction (n=22) or edema (n=4). Twenty-six of 76 (34%) patients, 11 (42%) with and 15 (58%) without decreased TOI, had cerebral events but neither absolute TOI nor its decrease from baseline was predictive (p=0.206). Conversely, in patients with events, the incidence of decreased TOI was not different (11 vs. 15 of 26; 42% vs. 58%; p=0.206), whereas duration of hypothermic circulatory arrest (59min ± 34 vs. 43 ± 33, p=0.049) and bilateral antegrade selective cerebral perfusion (66min ± 27 vs. 50 ± 26, p=0.013), hospital-stay (p=0.001), and mortality (p=0.014) were